#7 and #8 Head Valve Sizes

Thread Tools
 
Search this Thread
 
Old Nov 22, 2023 | 05:51 AM
  #1  
Tom Canfield's Avatar
Thread Starter
Registered User
 
Joined: Oct 2016
Posts: 36
From: Ohio
#7 and #8 Head Valve Sizes

Hello everyone,

I am working on refurbishing a pair of #7A (subcript 'A' from '72) Heads for an upcoming engine build, and I noticed a couple of the valves had some minor damage on the top of the stems. Some scoring and chips mostly. It is probably superficial, but I do not want to take the chance that the scoring would damage the rocker arms over time, and possibly lead to other problem down the road.

I happen to have a 350 parts engine as well, with #8 heads on it.

I am wondering if the intake and exhaust valves on the #8 heads are the same size as on the #7A Heads.

This is not a high dollar build I am going for, so saving a few bucks and not having to buy new valves is appealing to me. But I also do not want to tear down the 350, just to find out the valves do not match.

Thanks in advance for any help on this!
Old Nov 22, 2023 | 08:37 AM
  #2  
BillK's Avatar
Registered User
 
Joined: Dec 2016
Posts: 1,986
From: Beautiful Southern Maryland
Decent stock replacement valves are less than $10 each. If you only need a few its probably going to be easier to just order some. Or depending on how they actually look any automotive machine shop should be able to lightly grind the tips on the ones you have.
Old Nov 22, 2023 | 08:40 AM
  #3  
brownbomber77's Avatar
Registered User
 
Joined: Apr 2012
Posts: 1,606
From: Bradenton, FL
If you're getting a valve job anyway, may as well throw bigger valves in it. Very cheap power. You can also get Speedmaster stainless valves as another inexpensive option.
Old Nov 22, 2023 | 10:20 AM
  #4  
Tom Canfield's Avatar
Thread Starter
Registered User
 
Joined: Oct 2016
Posts: 36
From: Ohio
Thank you for the responses, however the heads are not going to have a full valve job, and having one performed is way out of budget. I plan to clean the carbon off the current valves, and lap them to clean up the valve seats, and that is it.

As far as replacing valves with stock OEM parts, that is not out of the question, but I have had contrasting answers on the size of valves that the 350 7a heads have. Some tell me that all 350 heads had the same valve size (except for the W-31 engines) and others tell me that the each head designation (#6, 7, 7a, 8, etc) had different sized valves. And I am have a hard time finding a definitive source on this.

But as I mentioned, if I can use the valves from the #8 heads, that will be my cheapest and easiest option.

Below is a picture of the valve damage, which is on at least 8 of the valves. No clue what caused this, as the heads came off of a parts car.

Old Nov 22, 2023 | 10:45 AM
  #5  
BillK's Avatar
Registered User
 
Joined: Dec 2016
Posts: 1,986
From: Beautiful Southern Maryland
The one that is beat up a little will probably clean right up on the valve refacer. Do you have a machine shop local ? I probably wouldn't even charge you to do a couple if you brought them here

My parts books only show the different valve sizes by year. Not by head number.
Old Nov 22, 2023 | 10:47 AM
  #6  
Tom Canfield's Avatar
Thread Starter
Registered User
 
Joined: Oct 2016
Posts: 36
From: Ohio
Thanks for the response Bill, I will give my local shop a call after the holidays and ask. Worst they can say is 'no' right?
Old Nov 22, 2023 | 11:10 AM
  #7  
BillK's Avatar
Registered User
 
Joined: Dec 2016
Posts: 1,986
From: Beautiful Southern Maryland
I cant imagine them saying no. Just ask them if they can "butt" a couple of valves.
Old Nov 22, 2023 | 01:51 PM
  #8  
edzolz's Avatar
Registered User
 
Joined: Nov 2009
Posts: 3,009
From: Red Oak, Texas
This looks like the heads have rotators. Looks to me like the rotators are not working. All of the damage is in one spot on the tip.
Old Nov 24, 2023 | 12:29 AM
  #9  
Altered 1978 350 Olds's Avatar
Registered User
 
Joined: Feb 2023
Posts: 43
I have 1972 7A heads and 1976 8 heads, both had the same valves when I did put them side by side.

Check your parts engine pistons when you disasämble it. That engine should have the smaller CC pistons compared to the 7A head engine.
Might consider to do put the 7A heads on the parts engine, use that as your rebuild core, or use the pistons from the parts engine in your build (if the bore is the same, not bored over at one time), to bump up the compression.

Last edited by Altered 1978 350 Olds; Nov 27, 2023 at 01:50 AM.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
olds 307 and 403
Small Blocks
4
Apr 8, 2016 07:06 AM
Seff
Small Blocks
3
Sep 21, 2013 08:45 AM
76Supreme350
Parts Wanted
9
Nov 9, 2010 01:17 PM
The_Jeremiah
Small Blocks
9
Sep 26, 2007 04:29 PM
455nova
Big Blocks
2
Mar 26, 2007 08:29 PM




All times are GMT -7. The time now is 05:42 PM.